Sowing dates effects on physiological, morphological andagricultural characteristics of maize (Zea mays L.)

In this study, it was aimed to determine the physiological, morphological and agricultural properties of maize grown in different sowing times in Amik Plain conditions. The study was carried out in 2019 and 2020 in HMKU Faculty of Agriculture Research and Application Area according to split plots in randomized complete blocks design with three replications. Four different sowing dates (EZ1, EZ2, EZ3, EZ4) were in the main plots and three different commercial hybrid maize varieties (77MAY35, DKC6630, P2088) were in the sub plots. In addition to the agricultural characteristics of the varieties grown in different sowing times, morphological and phenological characteristics such as emergence period, tasseling period and silking period and the date of reaching development stages (V6, V12, VT, R3, R5, R6) and growing degree days (GDD) values between these development stages were calculated. Some physiological parameters such as dry matter amount, leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), relative growth rate (RGR) and net assimilation rate (NAR) were examined. As a result of the study, it was determined that the plants reached physiological maturity in a shorter time with the delay of the sowing dates, but the total GDD values were increased. In addition to the dry matter amounts determined in different growth periods, it was established that all physiological parameters examined were significantly affected by sowing dates. Although there was no statistical differences in grain yield, the highest grain yield was obtained at the second sowing date. It was determined that maize sowings could be done in our region and in similar ecological conditions between 1 March and 15 April. However, it should be considered that there were difficulties in cultural practices such as tillage and cultivation due to the meteorological conditions in March and plants stay in the field for a longer time in early sowings, so extra input and labor is required.